23. The United States took several measures to curtail British blockade runners
Anthracite coal in Great Britain was imported from the United States and to a lesser extent Canada. When spies in Nassau, St. George, and other island ports reported its presence, where it had been shipped, the United States government passed legislation banning its exportation for the duration of the war. The British were forced to use bituminous coal, most of which came from mines in Wales. Bituminous coal burned with less heat and created more smoke, which was darker than that produced by anthracite coal. It made ships using it as fuel easier to spot at a greater distance.
The legal action to ban the export of anthracite coal was just one of the many measures taken by the United States to fight blockade runners. But it rigidly adhered to international law. Captured citizens of non-belligerent foreign nations were detained only long enough for authorities to ascertain they were who they claimed to be. They were released, and many returned to Nassau and British control by US Navy ships. One example of the practice can be found in the story of the blockade runner Banshee, built in Britain, manned by a British crew, and owned by a British company. Its Captain, Jonathan Steele, was a British officer.